DE 10 2009 034 616 A1 discloses a control assembly which takes the form of a load-sensing (LS) control. In this control the highest load pressure is signaled to a variable-displacement pump and the latter is controlled in such a way that a pump pressure exceeding the load pressure by a specific pressure differential Δp prevails in a pump line. Individual pressure compensators, which also maintain a constant pressure differential over the supply metering orifices of the hydraulic consumers having a lower load pressure at any given time, are assigned to adjustable supply metering orifices of the LS control for the consumers. The individual pressure compensators are usually arranged upstream of the supply metering orifices and restrict the fluid flow between the pump line and the supply metering orifices to such a degree that irrespective of the pump pressure the pressure upstream of the supply metering orifices still only exceeds the individual load pressure by a specific pressure differential. In the event of a supply deficit the consumer at the highest load pressure becomes slower, because the pump pressure issuing from its supply metering orifice falls and the pressure differential over this supply metering orifice thereby diminishes.
In this LS control a highest load pressure is signaled to a pump control of the variable-displacement pump usually via LS signal lines, which are interconnected by way of a shuttle valve cascade. This gives rise to a considerable outlay for mechanical devices, takes up a lot of overall space and is cost-intensive. In order to afford an adequate control pressure gradient at the supply metering orifices in these LS controls, the variable-displacement pump needs to provide an increased control pressure gradient at the individual pressure compensators, particularly in order to be able to compensate for influences on the fluid flow due to temperature changes or due to flow resistances. The control pressure gradient ensures that an adequate pressure differential prevails at the supply metering orifices in all operating states.
The Rexroth data sheet RD 66 134 discloses a hydraulic circuit diagram for the LS control explained above.
The publication U.S. Pat. No. 5,305,789 A discloses a load-independent flow distribution (LUDV) control. In a LUDV control the individual pressure compensators are arranged downstream of the supply metering orifices and restrict the fluid flow between the supply metering orifices and a load to such a degree that the pressure downstream of all supply metering orifices is equal, preferably equal to or slightly in excess of the highest load pressure. Here nothing changes in the event of a pressure supply deficit on the pressure downstream of the supply metering orifices. The pump pressure increases in the same way upstream of all supply metering orifices, so that the pressure differential varies in the same way at all supply metering orifices if the pump pressure diminishes in the event of a supply deficit, and the flow distribution between the supply metering orifices is maintained. Determination of a maximum load pressure relies on the fact that only the individual pressure compensator at the highest load is fully opened. Only in the fully opened position of the individual pressure compensator is its load pressure connected to a LS signal channel.
The Rexroth data sheet RD 64 125 discloses a hydraulic circuit diagram for the generic LUDV control.
DE 10 2007 045 803 A1 discloses a control assembly in which positions of valve spools of the individual pressure compensators are measured and the individual pressure compensators control the pressure differential at the supply metering orifice assigned to them. Here a displacement of a hydraulic pump is electrically adjusted as a function of the measuring result. This relies on the fact that only the valve spool of the individual pressure compensator at the highest load is fully opened.
The object of the disclosure, on the other hand, is to create a hydraulic control assembly which, in particular, is roughly functionally equivalent to the LS control and/or the LUDV control, which is of simple design, takes up little overall space, has a lower power requirement and is cost-effective.